. Plant anatomy from the standpoint of the development and functions of the tissues, and handbook of micro-technic. Plant anatomy. 196 STORAGE OF FOOD AND WATER divides tangentially and gives rise to several cell-layers constitut- ing a typical water-storage tissue (Fig. 79). Water-storage tracheids sometimes occur as terminals of the finer branches of leaf veins, as in Euphorbia splendens and Townsendia cespitosa (Fig. 107); and occasionally the meso- phyll cells have the characteristic wall thickenings of tracheids and apparently serve in water storage. The tubers of the potato and other fle
. Plant anatomy from the standpoint of the development and functions of the tissues, and handbook of micro-technic. Plant anatomy. 196 STORAGE OF FOOD AND WATER divides tangentially and gives rise to several cell-layers constitut- ing a typical water-storage tissue (Fig. 79). Water-storage tracheids sometimes occur as terminals of the finer branches of leaf veins, as in Euphorbia splendens and Townsendia cespitosa (Fig. 107); and occasionally the meso- phyll cells have the characteristic wall thickenings of tracheids and apparently serve in water storage. The tubers of the potato and other fleshy underground parts serve for the stor- age of water as well as of Fig. 107.—Water-storage tracheids in the leaf of Euphorbia splendens. b, b, water- storage tracheids; d, mesophyll cells; c, branch from a milk tube. (After Haberlandt.) Frequently, and especially in xerophytes, cells or groups of cells contain mucilage as a real cell content or as much thick- ened cell-walls, the inner layers of which have become transformed from cellulose to mucilage. Mucilage has a great affinity for water, imbibing it with power and holding it with great tenacity. When the amount of mucilage is considerable, as is frequently the case in desert plants, such as the Aloes, cacti, certain species of Astragalus, and many others, it plays an important part in the water-storage 'function. Characteristics of Water-storage Tissues.—The water- storage cells are characterized by having thin cellulose walls, or walls, if thickened, having many pits or thin places. These cells readily imbibe water when plenty is at hand, and when the soil water is scarce they deliver their stores gradually to those tissues, such as the photosynthetic and meristematic, in. Please note that these images are extracted from scanned page images that may have been digitally enhanced for readability - coloration and appearance of these illustrations may not perfectly resemble the original Stevens, William Ch
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